Global Microbe Study Finds ‘Black Market’ of Superbug Genes

Researchers have discovered an underworld of genetic exchange among bacteria, one more vast than previously imagined.

A comparison of thousands of bacterial genomes from around the world found genes flowing easily between species separated by hundreds, even thousands of miles. Whether the bacteria were related or not didn’t matter — a fascinating phenomenon on its own, but disturbing when the genes involved could turn pathogens into drug-resistant superbugs.

“We should have done this study and asked these questions five years ago,” said microbiologist Eric Alm of MIT, leader of a study published online Oct. 30 in Nature. “The significance was off the charts.”

Bacteria readily exchange DNA between closely related species, and much less frequently across unrelated lineages. This so-called horizontal gene transfer fuels adaptation, allowing for rapid adjustments to local pressures. Its full extent, however — especially in bacteria associated with humans, including those in our bodies, where bugs outnumber cells by 10 to 1 — are unknown.